Alta’s cells deliver more electricity per square-inch than rivals’ products, Norris said. That cuts weight, making them well-suited for unmanned aircraft, and for charging consumer devices such as phones and Apple Inc.’s iPad tablet. Adding solar to mobile phones may generate as much as $20 billion in industry sales through 2016, he estimated. “You can generate the same amount under the sun with an iPad cover as what you can get from the wall,” Norris said by phone. Consumer devices with built-in solar components “will become commonplace in the not-too-distant future.” Adding about a watt of Sunnyvale, California-based Alta’s solar cells to consumer devices such as smartphones would add $2 to $4 to the total materials cost, he said. Qualcomm Inc. said in November that it expects 5 billion smartphones to be sold globally from 2012 to 2016. “With one watt each, that’s 5 giga...